Now is time for cool heads to prevail, the Deputy Secretary-General told members of the Security Council as they debated the crisis in Ukraine.

The Council has been holding emergency consultations on Ukraine and the Autonomous Republic of Crimea since Friday.

Ukraine has been witnessing violent unrest for several months and last week saw the removal by parliament of President Viktor Yanukovitch.

Jan Eliasson shared the latest developments with the Council that he described as "serious".

"In Crimea, key sites such as airports, communications and public buildings, including the regional parliament, reportedly continue to be blocked by unidentified armed men. There are further reports of armed personnel taking control of regional administration buildings in several cities in the east and south of Ukraine. The new Crimean Prime Minister, Sergei Aksenov, today released a statement appealing to President Putin "to provide assistance in ensuring peace and tranquillity on the territory of the Autonomous Republic of Crimea".

The Russian Federation's Upper House of Parliament has approved a request of President Putin for Russian forces to be used in Ukraine, Eliasson shared.

Quoting the new Crimean Prime Minister, Eliasson said the forces will remain there "pending the normalization of the public and political situation in that country".

However, Eliasson noted, the calls for dialogue to all the concerned parties both inside and outside of Ukraine appear to be resonating.